I sometimes have to wipe track 0 from a hard
drive to do a clean install/repair if it had been
formatted with NTFS/corrupted. Conceivably
that's where a "bug" can also reside. FDISK
won't fix this regardless of how many times you
run it, but there is this teeny, weeny utility called
"hardcure" that will. It's all over the Internet as
Hardcure.zip.

Also "MBRTool" is suppose to do this as well,
but it looks to be a more elaborate utility. You
can Google for that also.

-BC